The present invention relates to a fuel injection valve.
A fuel injection valve in the form of an electromagnetically actuated valve is described, for example in German Patent Application No. 38 31 196, in which a valve needle is formed from an armature, a tubular connecting piece and a spherical valve closing body. The armature and the valve closing body are connected by the connecting piece, the connecting piece serving as a direct closing body support to which the valve closing body is solidly attached by a welded joint. The connecting piece has a multiplicity of flow openings through which the fuel can exit from an interior passageway and flow outside of the connecting piece to the valve closing body or to a valve seat face cooperating with the valve closing body. In addition the roll-bent connecting tube has a longitudinal slot running its entire length, the hydraulic flow cross-section section of which is large so that fuel coming from the interior passageway can flow through it quickly. Most of the fuel to be injected already flows out of the connecting piece over its length, while a small remnant portion does not exit from the connecting piece until immediately at the sphere surface.
German Patent Application No. 197 12 590 is an electromagnetically actuated valve that has an axially movable valve needle composed of an armature, which is either itself a closing body support or is connected to a closing body support, and a spherical valve closing body. The closing body support here accommodates the valve closing body in a downstream end area of the valve closing body. To do this, the end area encompasses the valve closing body so that at least one channel directly connected with a longitudinal bore of the closing body support is formed on the surface of the valve closing body. The end area extends here beyond the equator of the valve closing body. A solid connection is achieved by edge-forming or press-fitting.
Shaping out diagonally running grooves or flattened zones on the surface of spherical valve closing bodies of fuel injection valves is already described, for example in U.S. Pat. No. 5,199,648 and German Patent Application No. 44 08 875, the grooves or flattened zones being used exclusively for angled impingement of the fuel to be injected. The flow toward these formed closing body geometries occurs in this case from outside a tubular connecting piece of the valve needle and not against the spherical surface starting from an inner opening of the connecting piece, which functions as a closing body support.
A fuel injection valve that has a valve needle with a spherical valve closing body can be inferred from U.S. Pat. No. 4,483,485. The spherical valve closing body can also be provided with a horizontal flattened zone that extends inside the connecting piece of the valve needle being used as the closing body support. In order to enable a flow of fuel from an inner opening of the connecting piece to the valve seat, either transverse openings or several slotted openings that open toward the valve closing body are provided in the wall of the connecting piece. For all embodiments of the valve needle described in this specification, an opening geometry specially built into the closing body support and requiring additional manufacturing or machining steps is needed for the outflow of the fuel.
The fuel injection valve according to the present invention has the advantage that it can be produced in an especially simple and economical manner. For this purpose a spherical valve closing body is provided with at least one flattened zone having an axial extension component and is solidly connected with a sleeve-shaped closing body support. The closing body support can be fabricated to be rotationally symmetric for this in a very simple way, without the necessity of incorporating any kinds of opening geometry for the outlet of fuel on its exterior contour. Thus all machining steps that are typically needed for such additional flow openings are omitted. The end area of the closing body support encompasses the valve closing body in such a way that it forms one or more channelsxe2x80x94corresponding to the number of flattened zonesxe2x80x94directly on the surface of the valve closing body through which fuel can flow unhindered from the interior longitudinal bore coming toward a valve seat face. In this way an optimal flow to the metering area of the valve is achieved with little manufacturing effort.
Additional advantageous embodiments and improvements of the fuel injection valve are possible.
It is advantageous to form the at least one flattened zone at an angle to the valve longitudinal axis of between 12 and 25xc2x0 and to have the flattened zone run beyond a spherical equator of the valve closing body in the downstream direction.
In a especially advantageous way an magent armature can itself be used directly as the closing body support so that together with the valve closing body a two part valve needle is formed. A valve needle of this type can be produced especially simply and economically, and due to the reduced number of parts has only a single connecting piece.